行轉列

例如：把圖1轉換成圖2結果展示

圖1

圖2

CREATE TABLE `TEST_TB_GRADE` (
  `ID` int(10) NOT NULL AUTO_INCREMENT,
  `USER_NAME` varchar(20) DEFAULT NULL,
  `COURSE` varchar(20) DEFAULT NULL,
  `SCORE` float DEFAULT ‘0‘,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

insert into TEST_TB_GRADE(USER_NAME, COURSE, SCORE)  values
("張三", "數學", 34),
("張三", "語文", 58),
("張三", "英語", 58),
("李四", "數學", 45),
("李四", "語文", 87),
("李四", "英語", 45),
("王五", "數學", 76),
("王五", "語文", 34),
("王五", "英語", 89);

行轉列SQL：

SELECT user_name ,
    MAX(CASE course WHEN ‘數學‘ THEN score ELSE 0 END ) 數學,
    MAX(CASE course WHEN ‘語文‘ THEN score ELSE 0 END ) 語文,
    MAX(CASE course WHEN ‘英語‘ THEN score ELSE 0 END ) 英語
FROM test_tb_grade
GROUP BY USER_NAME;

列轉行

例如：把圖1轉換成圖3結果展示

圖3

列轉行SQL：

select user_name, ‘語文‘ COURSE , CN_SCORE as SCORE from test_tb_grade2
union select user_name, ‘數學‘ COURSE, MATH_SCORE as SCORE from test_tb_grade2
union select user_name, ‘英語‘ COURSE, EN_SCORE as SCORE from test_tb_grade2
order by user_name,COURSE;

【轉載自：http://blog.csdn.net/jx_870915876/article/details/52403472】

MySQL行轉列與列轉行